We plan to evaluate the control of secretion of somatostatin, glucagon, and insulin using the perfused pancreas of rat, dog, and chicken. Morphological studies will be undertaken to search for evidence of cell-cell interactions in islets and to characterize regional variation of structure of the endocrine pancreas. Work on somatostatin biosynthesis will be carried out to determine rates of synthesis and how these correlate with secretory events. We will also study islet growth, development, and response to injury in the endocrine pancreas of neonatal rats. Our hope is that these studies will enhance our understanding of the pathophysiology of diabetes mellitus.